Knob locking device



Feb. 18, 1969 F. P. GILBERT KNOB LOCKING DEVICE Filed April 21, 1967United States Patent land Filed Apr. 21, 1967, Ser. No. 632,725 Claimspriority, application Great Britain, May 6, 1966,

20,191/ 66 US. Cl. 16-121 6 Claims Int. Cl. H01e /02; A47b 95/02; B65d25/28 ABSTRACT OF THE DISCLOSURE A knob in which rotation of a lockingmember expands a ring to lock the knob in any position.

The invention relates to a self-locking knob.

According to the present invention there is provided a self-locking knobincluding a fixed resilient ring member disposed about the spindle ofthe knob and so as to fit within a recess of the knob and anindependently rotatable locking member having a plurality ofsymmetrically-arranged radial extensions which, on rotation of thelocking member from a free to a locking position press the ring memberinto engagement with the wall of the recess thereby locking the knob inany desired angular position.

The ring member may be a split annular ring and the said extensions ofthe locking member may extend within the gaps between the sections ofthe ring when the locking member is in its free position.

The split ring may project from a disc, in which case it may be maderesilient by the inclusion of slits between the ring and the disc at theend of each section of the ring.

An embodiment of the invention will be described with reference to theaccompanying drawings:

FIG. 1 is an exploded perspective view of a potentiometer knob,

FIG. 2 is a horizontal section of the knob shown in FIG. 1.

In FIG. 1 there is illustrated a knob head for a potentiometer 1 whichis attached to a frame 2. The knob head 3 is mounted on one end of aspindle 4 protruding from a threaded bush 5 which forms part of thepotentiometer and which enables the potentiometer to be secured to theframe by means of a thin hexagonal nut 6. The end of the knob head has acylindrical recess (not shown) which houses a brass ring 7. The knobhead may be moulded with the ring 7 as an insert or the ring may have aninwardly-directed flange on its upper edge adapted to engage a structuredesigned to be secured to the spindle and over which the knob head isthen fitted. The ring is designed so as to fit loosely round tworing-sections 8 which are fixed to the frame 2. The sections have slits9 which provide resilient tongues 10.

The locking member 11 is rotatable about the knob spindle and has ahandle 12 and two opposing extensions 3,427,680 Patented Feb. 18, 196913 having curved edges 14. These extensions have a radius which isbetween that of the inner and outer radii of the sections, so that whenthese pieces are in the gap between the sections the knob is free torotate. However, rotation of the member, in a clockwise manner, willallow the extensions to slide in front of the tongues 10, forcing thetongues .10 outwards so that they press firmly against the surroundingring and lock the knob.

I claim:

'1. A self-locking knob comprising,

a spindle,

a knob-head mounted on one end of said spindle and having a recess ofcircular cross-section surrounding said spindle,

means for rotatably mounting said spindle on a frame,

a resilient ring member fitting within said recess of said knob head andarranged to be fixed to said frame,

a locking member rotatably mounted on said spindle,

means for rotating said locking member with respect to said spindle andsaid frame, and

a plurality of symmetrically-disposed extensions on said locking memberarranged to engage said ring member on rotation of said locking memberfrom a free to a locking position and to urge said ring member intolocking engagement with said knob-head.

2. A knob according to claim 1 in which said ring member comprises asplit annular ring having symmetrically-disposed sections and in whichsaid extensions extend 'within the gaps between said sections when saidlocking member is in said free position.

3. A knob according to claim 2 further comprising a cup-shaped memberhaving a base adapted to be fixed to said frame and having split wallsforming said split ring.

4. A knob according to claim 3, wherein said cupshaped member includesslits between said base and said walls and extending from the gapsbetween said sections.

5. A knob according to claim 4 further comprising a further ring fixedwithin said recess so as to form an internal wall of said recess againstwhich said ring member is urged when in locking engagement.

6. A knob according to claim 1 further comprising a further ring fixedwithin said recess so as to form an internal wall of said recess againstwhich said ring member is urged when in locking engagement.

References Cited UNITED STATES PATENTS 2,433,794 12/1947 Springman188--7 3 3,227,985 1/1966 Hardison et al. 338162 3,366,911 1/1968 Wilsonet al. 338-197 3,384,727 5/1968 Zavertnik et al. 200-169 XR DONALD A.GRIFFIN, Primary Examiner.

US. Cl. X.R.

